Age at presentation provides a clue to the cause of aortic stenosis, although obstruction generally develops slowly.
Congenital and bicuspid valve disease
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In congenital aortic stenosis, obstruction is present from birth or becomes apparent during infancy.
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Bicuspid aortic valves may take years to become obstructed as fibrosis and calcification develop.
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Patients with bicuspid valves may present as young to middle-aged adults or have a systolic murmur discovered incidentally. The stated typical age range for stenosis is 50–60 years.
Rheumatic and calcific disease
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Rheumatic aortic valve disease usually accompanies mitral valve disease. Stenosis typically occurs at 30–60 years.
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In older people, tricuspid aortic valves may become stenotic through fibrosis and calcification. Calcific aortic stenosis typically occurs at 70–90 years.